在倒计时后找到某个班级时会弹出警报

Question

所以我希望能够在页面上找到某个类时弹出警报。我希望在计时器之后执行此操作，并且每个类只执行一次，因此不是每次刷新。我有一个显示不同警报的网站，并希望在发生sevirty1时弹出窗口。我现在的代码是：

<tr id="31245a15-1815-4872-9631-59e885552933" class="severity1">
                <td>
                    <img class="icon alertIcon" src="/csm/images/icons/event_viewer.png" data-original-title="Event Log Alert">
                </td>
                <td>
                    <a href="/csm/profile/alerts/124234">Evy (Previder)</a> :
                    <a href="/csm/device/alerts/13085950">VDC-EX01</a> :
                    <a href="/csm/monitor/alertDetailsAjax/31245a15-1815-4872-9631-59e885552933" class="alert_detail_link fancybox.ajax" onclick="return false;">
                        OALGen skipped some entries in the offline address list '\Global Address List'.  To see which entries are affected, event loggin ... (Code: '' - Type: 'Critical, Error, Warning' - Desc: '')
                    </a>
                </td>
                <td align="right">
                    <span class="time" data-original-title="2018-06-06 06:09:12 CEST">
                        4 hours ago
                    </span>
                </td>
            </tr>




<script type="text/javascript">
        var countdown = 180;
        $('clock').update(new Date());
        setInterval(updateClock, 1000);

        function updateClock() {
            $('clock').update(new Date());
            $('countdown').update(countdown--);
            if (countdown < 1) {
                refreshKiosk();
                countdown = 180;
            }
        }

        function refreshKiosk() {
            widgetBody('asset_widget', true);
            widgetBody('component_widget', true);
            widgetBody('job_widget', true);
            widgetBody('alerts_widget', true);
            updateAlertsWidget('kiosk=true', true);
            countdown = 180;
        }

 function FindClass() {

var check = document.getElementsByName("severity1");
if(check)
{
      alert('Did not expect it');
}
}

    </script>

它不刷新页面只有警告，所以如果找到了servirty1类，弹出窗口需要显示。

warning looks like this